An image forming apparatus forms an image on a printing medium and includes a printer, a copier, a facsimile machine, a multi-function device combining functions of the aforementioned devices, and the like.
An image forming apparatus using electrophotography emits light onto a photosensitive body charged with a predetermined electric potential and then forms an electrostatic latent image on a surface of the photosensitive body, to thereby form a visible image by supplying toner onto the electrostatic latent image. The visible image formed on the photosensitive body may be directly transferred to a printing medium or transferred to the printing medium via an intermediate transfer body, and the visible image transferred to the printing medium may be fixed onto the printing medium while being passed through a fixing device.
In general, a belt-type fixing device is equipped with a heat source, a heating member made of a belt, and a pressing member contacting tightly to the heating member to form a fixing nip. When the printing medium to which a toner image is transferred is fed between the heating member and the pressing member, the toner image is fixed onto the printing medium by heat radiating from the heating member and pressure applying to the fixing nip.